Wash the crabs well and then cut them in half with a large cleaver. Rinse them in running water and remove the gills and spongy yellow parts. Coat the crabs in flour.

In a skillet, heat 2 tablespoons of peanut oil under medium heat. Fry the crabs until the shells turn red. Turn at least once. Transfer the crabs to a plate.

3-5 minutes or until the onions are soft. Add the ketchup, oyster sauce, tamarind paste, chili paste, grated cloves and soy sauce. Bring it to a boil and let it simmer for 5-10 minutes. Add the crab to the sauce until the meat is cooked and it turns white.